One of the ships that Shell Oil plans to use to drill in the Arctic slipped its mooring and drifted close to one of Alaska's Aleutian Islands, the latest in a string of incidents to arise around the controversial project.

The Noble Discoverer was about 175 yards from shore in Unalaska Bay when it slipped its mooring Saturday and drifted towards shore near Dutch Harbor, Coast Guard Petty Officer Sara Francis said.

"There are no reports of injuries, pollution and damage to the Noble Discoverer," she said Sunday night.

The incident raised concerns of a possible grounding near Dutch Harbor, though Francis said there was "no damage to the hull or evidence it ran aground."

The Noble Discoverer is one of roughly two dozen ships that Shell is sending to the Beaufort and Chukchi seas in the Arctic to drill exploration wells in the harshest climate in the world.

Pete Slaiby, the vice president of Shell Oil in Alaska, told CNN recently the drilling in the arctic would be the "most complex, most difficult wells we've drilled in company history."

Proponents say if Shell finds oil with its Arctic drilling, it could create thousands of jobs; opponents -- Alaska's Inuit Eskimos and environmentalists -- say an oil spill could pollute the waters and damage the economy.

"Our subsistence for the winter, it all comes from the ocean, the fish and whale. It's going to ruin our ocean," 79-year-old Abagail Nashupuq of Point Hope told CNN recently.

Nashupuq has spent her entire life in the small northwest fishing village of Point Hope, which sits about 90 miles from where Shell plans to drill one of its exploratory wells in the Chukchi Sea.

Shell has been forced to postpone drilling, which was scheduled to begin this month, until August by an unexpected thick ice pack.